Automated swimming pool cleaners have been developed for the cleaning of the bottom and side walls of pools by programming the electrically-powered cleaner to traverse the bottom of the pool in one direction, and climb the side wall of the pool that it encounters until the leading end of the cleaner emerges at the waterline of the pool. Thereafter, the drive mechanism is reversed which causes the pool cleaner to reverse direction and to descend the vertical side wall until it encounters the bottom of the pool, at which point it undergoes a transition to return to a generally horizontal position to again begin its traverse of the bottom of the pool. By means of various structural and/or electro-mechanical devices operated in response to a preprogrammed microprocessor controller, the pool cleaner can be made to traverse an ever-changing, but generally predictable pattern across the bottom and up and down the side walls of the pool in order to clean the entire bottom surface. The pool cleaner also traverses horizontally along the side wall of the pool to clean the so-called scum line that often forms at the waterline.
Pool cleaners of the prior art are designed to operate at a substantially continuous speed, whether they be driven by electric motors or water turbines. Minor variations in speed may occur at the transition zone where the pool cleaner moves from a generally horizontal position at the bottom of the pool to assume a vertical position on the side wall, and vice-versa. Other minor variations may be observed when the direction of travel of the pool cleaner is reversed, for example, when the pool cleaner begins its descent from the waterline along the side wall of the pool. Further minor variations between the speed at which the cleaner traverses the bottom of the pool and that at which it ascends and/or descends along the side wall due to gravitational effects which act upon the cleaner despite its neutrally buoyant design. However, these variations in speed are relatively minor and do not occur as a result of the preprogrammed operation of the cleaner and do not improve the functioning of the cleaner.
Swimming pool cleaners of the prior art operate at speeds in the range from about five feet per minute to ten feet per minute. Depending upon the size of the pool to be cleaned, the unit may have to be placed in operation for as long as six to eight hours to clean a large municipal or commercial swimming pool. The cleaning of larger pools must be done when the pool is not in use, generally overnight, over a weekend, or at other times when it is not convenient or economical to have maintenance personnel on duty to attend the cleaning of the pool. Although the power supply to the pool cleaner can be put on a timer, various circumstances can arise that will interfere with, or entirely interrupt the operation of the cleaner so that only a portion of the pool has been cleaned during the allocated cycle. For example, the floating power cord can become entangled, thereby disrupting the programmed cleaning pattern; the cleaner can become trapped in a corner, or against a ladder or other obstruction at the side of the pool.
In order to permit the pool cleaner to traverse the bottom of the pool and to ascend and descend the side walls of the pool during its cleaning operations, the pool cleaner is of substantially neutral bouyancy with respect to the water in the pool. Thus, variations in water density between fresh water and salt water pools must also be taken into account in the construction of pool cleaners for these different environments. For example, additional weights can be attached to the cover and/or base plate of a pool cleaner that is neutrally buoyant with respect to fresh water in order to adapt it for use in a salt water pool. As will be understood by one familiar with the art, when the pool cleaner ascends to the waterline to clean the wall surface at the scum line, a portion of the pool cleaner projects above the surface of the pool. Air enters the space between the cover and the base plate, and when the pool cleaner begins its descent along the wall, the air must be displaced by the water in order to maintain the designed neutral buoyancy of the cleaner. It has also been observed that when the pool cleaner is initially placed in the pool, the owner or maintenance personnel typically lowers the unit in a vertical position on the side wall and activates the power supply.
It has been found that when pool cleaners of the prior art are operated at higher speeds, the rapid descent from the waterline results in air becoming entrained in the space between the cover and base plate causing the cleaner to float away from its operating position and vertical alignment on the wall. If the air is not displaced, the cleaner will float at the surface of the pool; if the air is eventually displaced and the cleaner sinks to the bottom of the pool it can remain in an inoperable position with respect to the bottom of the pool, or if it does land upright on the bottom surface, its programmed pattern of operation will have been disrupted and areas of the pool will be left uncleaned.
It is therefore an object of the present invention to provide an apparatus and a method for increasing the speed at which the pool is cleaned, thereby reducing the overall operating time of the pool cleaner.
It is another object of the invention to provide a pool cleaner that operates at a speed that is significantly greater than that of commercially available pool cleaners of the prior art.
It is yet another object of the invention to provide a power-driven automated pool cleaner that will rapidly traverse the bottom and ascend the side walls of a pool and that will descend from the waterline while maintaining continuous operative cleaning contact with the side wall of the pool.
It is also an object of the invention to provide an apparatus and method for rapidly cleaning the side walls of pools a the scum line.
It is another important object of the invention to provide a pool cleaning apparatus that operates at speeds significantly greater than those of the prior art while maintaining its neutral buoyancy at all stages of its cleaning operations.